How do people divide up a tank into multiple sections for betta fish? For example, I've seen people divide a 20 gallon into 3 different "tanks" for bettas. I'd like to do that with a 10 gallon but I only want it divided in half so I can keep 2 bettas.

Do you mean a divider like this?

https://www.google.com/shopping/product ... M7EALw_wcB